Yuusha, Yamemasu Episode 6 Today

Leo was one of twelve "Demonheart" units created by humanity to fight off an invasion of "Demons" (which were actually extra-dimensional monsters). While the other units were eventually destroyed or deactivated, Leo's unique ability to "auto-evolve" and his immortality allowed him to survive indefinitely.

Leo explains that the world is not a typical fantasy realm but rather Earth in the far future . He is not a human born in this era but a bio-engineered weapon created 3,000 years ago. Yuusha, Yamemasu Episode 6

The "demons" Leo fought in the past were not the same as Echidna's army. Echidna’s people are actually a different race altogether, making the current conflict a tragic misunderstanding of history. 💡 Character Analysis: Leo Demonheart Leo was one of twelve "Demonheart" units created